<style>
  body {
    background: green;
  }
  iframe  {
    width: 100vw;
    height: 100vh;
    border: 10px solid red;
    transform: scale(.5);
  }
</style>
<iframe src="data:text/html,<body style='overflow: hidden; overflow-y: auto;'><div style='background: blue; height: 2000px'>"></iframe>
